package org.bouncycastle.asn1.x509;

import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.SimpleTimeZone;

import org.bouncycastle.asn1.ASN1Choice;
import org.bouncycastle.asn1.ASN1Encodable;
import org.bouncycastle.asn1.ASN1TaggedObject;
import org.bouncycastle.asn1.DERGeneralizedTime;
import org.bouncycastle.asn1.DERObject;
import org.bouncycastle.asn1.DERUTCTime;

public class Time extends ASN1Encodable implements ASN1Choice {
    DERObject time;

    public static Time getInstance(ASN1TaggedObject obj, boolean explicit) {
        return getInstance(obj.getObject()); // must be explicitly tagged
    }

    public Time(DERObject time) {
        if (!(time instanceof DERUTCTime)
                && !(time instanceof DERGeneralizedTime)) {
            throw new IllegalArgumentException("unknown object passed to Time");
        }

        this.time = time;
    }

    /**
     * creates a time object from a given date - if the date is between 1950 and
     * 2049 a UTCTime object is generated, otherwise a GeneralizedTime is used.
     */
    public Time(Date date) {
        SimpleTimeZone tz = new SimpleTimeZone(0, "Z");
        SimpleDateFormat dateF = new SimpleDateFormat("yyyyMMddHHmmss");

        dateF.setTimeZone(tz);

        String d = dateF.format(date) + "Z";
        int year = Integer.parseInt(d.substring(0, 4));

        if (year < 1950 || year > 2049) {
            time = new DERGeneralizedTime(d);
        } else {
            time = new DERUTCTime(d.substring(2));
        }
    }

    public static Time getInstance(Object obj) {
        if (obj == null || obj instanceof Time) {
            return (Time) obj;
        } else if (obj instanceof DERUTCTime) {
            return new Time((DERUTCTime) obj);
        } else if (obj instanceof DERGeneralizedTime) {
            return new Time((DERGeneralizedTime) obj);
        }

        throw new IllegalArgumentException("unknown object in factory: "
                + obj.getClass().getName());
    }

    public String getTime() {
        if (time instanceof DERUTCTime) {
            return ((DERUTCTime) time).getAdjustedTime();
        } else {
            return ((DERGeneralizedTime) time).getTime();
        }
    }

    public Date getDate() {
        try {
            if (time instanceof DERUTCTime) {
                return ((DERUTCTime) time).getAdjustedDate();
            } else {
                return ((DERGeneralizedTime) time).getDate();
            }
        } catch (ParseException e) { // this should never happen
            throw new IllegalStateException("invalid date string: "
                    + e.getMessage());
        }
    }

    /**
     * Produce an object suitable for an ASN1OutputStream.
     * 
     * <pre>
     * Time ::= CHOICE {
     *             utcTime        UTCTime,
     *             generalTime    GeneralizedTime }
     * </pre>
     */
    public DERObject toASN1Object() {
        return time;
    }

    public String toString() {
        return getTime();
    }
}
